In a conventional battery characteristic determining device disclosed in U.S. Pat. No. 7,692,410, a two-pulse current load that is switched between zero and twenty Amperes and that has a pulse width of ten seconds and an inter-pulse space of ten seconds is applied to discharge a battery module, such that a voltage of the battery module is decreased during the application of each pulse. C rate (i.e., charge/discharge rate) of the battery module is determined based on a variation of the voltage of the battery module due to the application of the second pulse, and a fully charged capacity of the battery module is determined based on the C rate of the battery module and the pulse height of the current load.
However, when implementing the conventional battery characteristic determining device in a vehicle to determine the C rate and the fully charged capacity of the battery module of the vehicle, design efforts and costs for a circuit that provides the two-pulse current load are incurred, and security issues may arise from discharging the battery module at will.